I a cut strips of o bike inner tube and glued to the pole then just glued the bike grip to it, I also but a small bot under the grip as they started to slide down a bit after about 10 days of use.
for the strap and bar end, buy a wooden rode that is the same internal diameter of the pole then glue that in to place. I used the bar end the came with the grips and cut the piece that sticks in to the handle bar off and drilled a hole in it then you screw both the strap and bar end to the rode in the pole. I used straps off rental poles which are easy to get at my resort
These have lasted me one and a half seasons so far.